JP2642649B2 - Body direction detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a traveling azimuth detecting device for detecting the azimuth of a vehicle body in the front-rear direction, that is, the reference direction of the vehicle body direction.

2. Description of the Related Art As a conventional traveling direction detecting device, a direction θ is set to θ = ta based on an x output and a y output of a two-axis output type geomagnetic sensor.
A device that calculates the value by the formula of n ^-1 (x / y) is known (for example, Japanese Patent Application Laid-Open No. 57-30668). However,
When using such a conventional traveling direction detection device, for example,
Geomagnetism changes depending on the place where the vehicle is used, and vehicles such as motorcycles move with rotation in three axes. Therefore, it is necessary to determine whether the two-axis output type terrestrial magnetometer alone detects the horizontal component of terrestrial magnetism accurately. Since it cannot be determined, an error may occur in the calculated orientation.

Further, even if the vehicle body is tilted, it is necessary to keep the geomagnetic sensor horizontal in order to accurately detect the geomagnetic horizontal component, and therefore, there is a type in which a gyro is used to hold the geomagnetic sensor. However, using a gyro increases the cost and has problems in durability and stability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a traveling azimuth detecting device for a vehicle body that can accurately detect an azimuth without using a gyro.

In the traveling azimuth detecting device of the present invention, a magnetic detecting means provided on a vehicle body for detecting magnetic components in three axial directions of terrestrial magnetism, and an azimuth relative to a reference direction of the vehicle body direction according to each output signal of the magnetic detecting means Computing means for calculating,
The calculating means detects a vertical component of terrestrial magnetism as an initial value based on an output signal of the magnetic detecting means when the vehicle body is in an upright state. When the magnitude of the calculated vertical component at the current location is within a predetermined range including the initial value, the azimuth of the vehicle body direction with respect to the reference direction is calculated, and the calculated vertical component at the current location is calculated. When the magnitude of the vertical component is not within a predetermined range including the initial value, the calculation of the azimuth corresponding to the reference direction of the vehicle body direction is stopped.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a motorcycle-equipped navigator provided with a heading detecting apparatus according to an embodiment of the present invention. This navigator is provided with a geomagnetic sensor 1 for detecting magnetic components of geomagnetism in three axial directions. As the geomagnetic sensor 1, for example, a single geomagnetic sensor disclosed in Japanese Patent Publication No. 62-51777 is provided integrally in three axial directions. The output of the geomagnetic sensor 1 is
The signal is converted into a digital signal by the A / D converter 2 and supplied to the microprocessor 3. Microprocessor 3
Is connected to a display device 5 via a drive circuit 4.
As shown in FIG. 2, the display device 5 has a numeric display 11 for displaying the bearing with respect to the north direction and an arrow display 12 composed of light emitting elements for displaying the direction in which the vehicle should travel with respect to the target direction. The display device 5 is provided at the front center of the handle pipe 13 of the motorcycle as shown in FIG. The microprocessor 3 is connected to a handle switch 6 composed of a non-locking push button switch for indicating a target direction. The handle switch 6 is fixed to a handle pipe 13 near a left handle grip 14 of the motorcycle by a support member 15 as shown in FIG. When the handle switch 6 is operated and turned on from off, the input level to the microprocessor 3 from the handle switch 6 is inverted from a high level to a low level. A non-lock type initialization switch (not shown) is connected to the microprocessor 3. This initialization switch needs to be operated with the vehicle body upright. Further, an alarm 17 such as a buzzer is provided on the vehicle.
Reference numeral 17 is connected to the microprocessor 3 via a drive circuit 18.

On the other hand, as shown in FIG. 4, the output voltage of the power supply (battery) 7 is made constant by the constant voltage circuit 8. The constant voltage is supplied via a short-circuit protection circuit 9 to a geomagnetic sensor 1 as a load, a D / A converter 2, a microprocessor 3, a driving circuit 4, 1
8. It is supplied to the display device 5 and the alarm device 17. The short-circuit protection circuit 9 includes, for example, a high impedance element such as a high resistor.

In such a configuration, the microprocessor 3 receives three-axis output (x output, y output and z output) from the geomagnetic sensor 1 and information indicating whether or not the direction of the target location can be detected from the steering wheel switch 6 to the microprocessor 3. Supplied. In addition,
The geomagnetic sensor 1 is mounted on the vehicle body so that the obtained x output represents a geomagnetic component in the left-right direction of the vehicle body, the y output represents a geomagnetic component in the front-rear direction of the vehicle body, and the z output represents a geomagnetic component in a direction perpendicular to the front-rear direction and the left-right direction of the vehicle body. The x output and the y output indicate the geomagnetic component in the horizontal plane when the vehicle is mounted and the vehicle is placed upright.

When detecting the operation of the initialization switch, the microprocessor 3 starts processing of a main routine shown in FIG. 5, first executes an initialization routine (step 21), and then executes an azimuth calculation routine (step 21) for detecting an azimuth. 22) and repeatedly execute the heading routine (step 23) to display the destination direction.

In the initialization routine, as shown in FIG. 6, first, the x output, the y output and the z output of the geomagnetic sensor 1 in the upright state of the vehicle body are read (step 31). Here, each value of the read x output, y output and z output of the geomagnetic sensor 1 is
Let x _i , y _i , z _i . After reading each output of the geomagnetic sensor 1, the total magnetic force at the current position of the vehicle body Is calculated from the following equation (step 32).

By the way, the actual horizontal component of the geomagnetism at the time of this initialization Can be represented as Where r is the radius of the earth,
M is the magnetic moment of the earth, the zeta _i the latitude of the current location of the vehicle on the earth. The vertical component of the current location Is Can be represented as

The geomagnetism of the dip angle at the time of initialization when the I _i, from equation (2), (3), Becomes Further, if K = M / r ^{3 where} K is the constant of the earth,
Equation (1) is obtained from equations (2) and (3). Can be expressed as Therefore, the microprocessor 3
Is After the calculation, to calculate the K ² from the following equation (step 33).

Where ζ _i is given by equation (4). Becomes

Total magnetic force when the body is kept upright Horizontal component Vertical component The relationship between the azimuth θ relative dip angle I _i and magnetic north (N) shown in Figure 7.

Next, in the azimuth calculation routine, as shown in FIG. 8, first, the magnetic forces of the x output, y output and z output of the geomagnetic sensor 1 are read (step 41). Here, each value of the read x output, y output and z output of the geomagnetic sensor 1 is
Let x _M , y _M , z _M. After reading each output of the geomagnetic sensor 1, the total magnetic force at the current position of the vehicle Square value and calculating the dip angle I _C of (step 42, 43). Total magnetic force Is the square of Becomes the total magnetic force Is the total magnetic force regardless of the rotation or tilt of the body Becomes equal to Assuming that the dip angle I _C is the latitude ζ of the measurement point, Where sinζ is similar to equation (6) Holds, so Can be expressed as

When the microprocessor 3 calculates the dip angle I _C , the vertical component at the current position of the vehicle body is calculated. And horizontal component Is calculated by the following equation (step 44).

Calculated vertical component Is the initial value of the vertical component Is determined to be within the allowable value Z _i ± | ΔZ | (step 45), and | Z _c | <| Z _i | − | ΔZ | or | Z _c |> | Z _i + | ΔZ |
If so, an alarm command is issued to the drive circuit 18 to activate the alarm 17 (step 46). By the generation of this alarm, for example, the driver operates the above-mentioned initialization switch to execute the initialization routine so as to take each initial value again.

On the other hand, if | Z _i | − | ΔZ | ≦ | Z _c | ≦ | Z _i + | ΔZ |
The current azimuth θd with respect to the direction (Step 47), and the calculated current direction θ
A numerical display command representing d is issued to the drive circuit 4 (step 48). The drive circuit 4 displays the azimuth θd indicated by the instruction on the numeral display 5 in response to the numeral display instruction.
When a vehicle such as a motorcycle travels straight, the vehicle body tends to be horizontal in the left-right direction. Therefore, the azimuth θd can be set to a value ignoring the left-right inclination of the vehicle body.

Next, in the heading routine, as shown in FIG. 9, it is first determined whether or not the absolute value of the difference between the current azimuth θd and the azimuth θh of the destination is 180 ° or less (step 51). The azimuth θh of the destination is determined in step 61 described later by turning on the handle switch 6. However, the direction θh is an initial value until the handle switch 6 is turned on. | Θd-θh | if ≦ 180 °, the current orientation [theta] d and orientation theta _D, the orientation [theta] h of the target value and orientation theta _H (step 52). | Θd-θh |> If 180 °, the orientation [theta] h of the target value and orientation theta _D, current heading [theta] d
The the orientation theta _H (step 53). After setting this orientation theta _D and orientation theta _H, determines whether the orientation theta _D and the azimuth theta _H are equal (step 54). If θ _D = θ _H , an arrow display stop command is issued to the drive circuit 4 (step 5).
Five). The drive circuit 4 stops displaying the arrow indicator 12 in response to the arrow display stop command. If θ _D ≠ θ _H , it is determined whether the azimuth θd is greater than the azimuth θ _H (step 5).
6). If θ _D > θ _H , the left arrow display command is sent to the drive circuit 4
(Step 57). If θ _D > θ _H is not satisfied, it is determined whether or not the azimuth θ _D is paired with the azimuth θ _H (step 58). If θ _{D <θ H,} generates the right arrow display command to the drive circuit 4 (step 59). The drive circuit 4 displays “←” on the arrow display 12 in response to the left arrow display command.
Is displayed, and “→” is displayed on the arrow display unit 12 in response to the right arrow display command. Step 58 may be omitted. After the display command is issued, it is determined whether or not the steering wheel switch 6 is turned on (step 60). When the steering wheel switch 6 is turned on, the current azimuth θd is set to the azimuth θh of the destination (step 61). That is, since the steering wheel switch 6 is determined to be turned on when the vehicle body is turned to the destination, the current azimuth θd calculated by the azimuth calculation routine when the steering wheel switch 6 is turned on is the azimuth θh of the destination.

For example, as shown in FIG. 10, if the traveling direction is true north (azimuth 0 °) when the target point T is located at an azimuth 45 ° in the northeast at the current point P, the arrow indicator 12 indicates “→ Is displayed. The heading is in the northeast direction
In the case of the B direction of 60 °, “←” is displayed on the arrow display 12.

Effect of the Invention As described above, in the traveling direction detecting device of the present invention,
A vehicle body is provided with magnetic detecting means for detecting magnetic components in three axial directions of geomagnetism, and an azimuth of a vehicle body direction with respect to a reference direction is calculated according to each output signal of the magnetic detecting means. That is, the horizontal component and the vertical component of the terrestrial magnetism can be obtained from each output signal of the magnetic detection means, so that the azimuth can be accurately calculated. In addition, since the configuration is simplified without using a gyro, the cost is reduced, and the durability and stability can be improved since there are no movable parts. Further, a vertical component of the terrestrial magnetism is calculated based on the output signals of the magnetic components in the three axial directions of the magnetic detecting means. Since the azimuth is calculated, the azimuth can be obtained with high accuracy at the time of the azimuth calculation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a motorcycle mounted navigator provided with a heading detection device according to one embodiment of the present invention, FIG. 2 is a diagram showing a display device, and FIG. 3 is a diagram showing a display device and a handle switch in a motorcycle. FIG. 4 is a block diagram showing a power supply unit of the navigator of FIG. 1, and FIG.
FIGS. 6, 6, 8 and 9 are flowcharts showing the operation of the microprocessor, and FIG. 7 is the total magnetic force. Horizontal component Vertical component Diagram showing the relationship between azimuth θ relative dip angle I _i and magnetic north (N),
FIG. 10 is a diagram showing a relationship between a target location and a vehicle traveling direction for indicating a heading operation of the navigator. Explanation of reference numerals of main parts 1 ... geomagnetic sensor 3 ... microprocessor 5 ... display device 6 ... handle switch 9 ... short circuit protection circuit 17 ... alarm

Claims (2)

(57) [Claims] 1. Magnetic detecting means provided in a vehicle body for detecting magnetic components in three axial directions of terrestrial magnetism, and calculating means for calculating an azimuth of a vehicle body direction with respect to a reference direction in accordance with each output signal of the magnetic detecting means. The traveling direction detecting device having: The arithmetic unit detects a vertical component of terrestrial magnetism as an initial value based on an output signal of the magnetic detecting unit when the vehicle body is in an upright state, and after detecting the initial value, Calculating the vertical component of the geomagnetism at the current position based on each output signal of the magnetism detection means, and when the calculated magnitude of the vertical component at the current position is within a predetermined range including the initial value, When the magnitude of the calculated vertical component at the current point is not within a predetermined range including the initial value, the direction corresponds to the reference direction of the vehicle body direction. Traveling direction detection device, characterized in that to stop the position calculation. 2. The traveling azimuth according to claim 1, wherein said calculating means has an alarm generating means for issuing an alarm when the calculated magnitude of said vertical component is not within said predetermined range. Detection device.